Tongue lock for stackable containers

Abstract

A tongue shaped friction lock is integrally formed in a dust cover or a bottom panel of an open-topped container and positioned to capture the stacking tabs of an adjacent open-topped container. The friction lock provides a small opening through which a stacking tab may be inserted, while at the same time pushing up a locking flap, which pivots up and frictionally engages the stacking tab. A strip of reinforcing tape is embedded within the dust cover and allows one to remove and reuse the dust cover without tearing the tongue lock or the surrounding portions of the dust cover.

1 - 21 . (canceled) 
   
   
       22 . A frictional locking mechanism formed in a flexible material for engaging at least one stacking tab of a sub-adjacent article, comprising
 at least one flap comprising a front edge, a back pivot line, and two side edges; and   at least one cut-out slot in said flexible material comprising a top wall and two side walls, wherein   said front edge of said at least one flap protrudes into said at least one cut-out slot towards said top wall of said at least one cut-out slot;   said front edge of said at least one flap is spaced from said top wall of said at least one cut-out slot a distance that is less than a thickness of said stacking tab when said locking mechanism is not engaging with said at least one stacking tab; and   said flap can pivot along said back pivot line in an upwards direction when engaging said at least one stacking tab.   
   
   
       23 . The frictional locking mechanism according to  claim 22 , wherein said front edge of said at least one flap is arcuate. 
   
   
       24 . The frictional locking mechanism according to  claim 22 , wherein said at least one flap is tongue-shaped. 
   
   
       25 . The frictional locking mechanism according to  claim 22 , wherein said two side edges of said at least on flap create a portion of said two side walls of said at least on cut-out slot. 
   
   
       26 . The frictional locking mechanism according to  claim 22 , wherein said at least one flap comprises at least one perforated pivot line that enables the flap to pivot back and forth. 
   
   
       27 . The frictional locking mechanism according to  claim 22 , wherein each of said at least two side walls of said at least one cut-out slot are made from incisions that extend entirely through the thickness of said flexible material. 
   
   
       28 . The frictional locking mechanism according to  claim 22 , wherein said at least one flap is frictionally engaged with the at least one stacking tab of a sub-adjacent article. 
   
   
       29 . The frictional locking mechanism according to  claim 22 , wherein said top wall of said at least one cut-out slot is defined by at least one narrow strip of said flexible material, said at least one narrow strip of flexible material positioned between said slot and an adjacent free edge of said flexible material. 
   
   
       30 . The frictional locking mechanism according to  claim 29 , further comprising at least one reinforcing material extending through a portion of said at least one narrow strip of flexible material. 
   
   
       31 . The frictional locking mechanism according to  claim 30 , wherein said at least one reinforcing material is embedded in said flexible material. 
   
   
       32 . The frictional locking mechanism according to  claim 22 , further comprising at least one reinforcing material embedded in said flexible material. 
   
   
       33 . The frictional locking mechanism according to  claim 32 , further comprising at least one reinforcing material surrounding said at least one cut-out slot. 
   
   
       34 . The frictional locking mechanism according to  claim 33 , further comprising at least one reinforcing material extending through said at least one flap. 
   
   
       35 . The frictional locking mechanism according to  claim 22 , further comprising at least one reinforcing material surrounding said at least one cut-out slot. 
   
   
       36 . The frictional locking mechanism according to  claim 35 , further comprising at least one reinforcing material extending through said at least one flap. 
   
   
       37 . A container, comprising at least one frictional locking mechanism according to  claim 22 . 
   
   
       38 . A cover, comprising at least one frictional locking mechanism according to  claim 22 . 
   
   
       39 . A blank, comprising at least one frictional locking mechanism according to  claim 22 . 
   
   
       40 . A method of making a container or cover, comprising forming at least one frictional locking mechanism according to  claim 22  in said container or cover. 
   
   
       41 . A method of increasing the ability of a container or cover to secure and hold stacking tabs of a sub-adjacent container or cover, comprising folding a blank into said container or cover, said blank comprising at least one of frictional locking mechanism according to  claim 22  in said container or cover.